AWS Route 53 Routing Policies: SAA-C03 Guide

Amazon Route 53 is a highly available and scalable Domain Name System (DNS) web service. Beyond simple domain registration, its “Routing Policies” determine how Route 53 responds to queries, effectively acting as the traffic cop for your global infrastructure.

The Real-World Analogy

Imagine a global pizza franchise.

• Simple: You call one number, and they give you the address of the nearest shop.
• Weighted: 70% of callers are sent to the main kitchen, 30% to a new test kitchen.
• Latency: You are automatically connected to the kitchen that can deliver to you the fastest.
• Failover: If the local shop is on fire, your call is automatically diverted to the next town over.

Core Routing Policies

1. Simple Routing

The most basic policy. It typically routes traffic to a single resource (e.g., one web server). You can specify multiple values in one record (like multiple IP addresses), but Route 53 returns all values in a random order to the client.

2. Weighted Routing

Used to route traffic to multiple resources in proportions that you specify. This is ideal for Canary Testing or Blue/Green Deployments. If you assign a weight of 0 to a resource, Route 53 stops sending traffic to it.

3. Latency-based Routing

Routes traffic to the AWS Region that provides the lowest network latency for the user. It is based on measurements taken over time and does not necessarily mean the geographically closest region.

4. Failover Routing

Used for Active-Passive disaster recovery. Route 53 monitors the health of the primary resource. If it fails, traffic is automatically routed to a secondary (DR) resource.

5. Geolocation Routing

Routes traffic based on the physical location of your users (Continent, Country, or US State). This is critical for Compliance (GDPR) or Content Localization (showing different languages).

6. Geoproximity Routing

Routes traffic based on the geographic location of your users and your resources. You can optionally expand or shrink the size of a geographic region by specifying a Bias. This requires Route 53 Traffic Flow.

7. Multi-value Answer Routing

Similar to Simple Routing but allows you to check the health of each resource. Route 53 returns up to eight healthy records in response to a DNS query.

Comparison Table

Policy	Primary Use Case	Health Checks?	Key Benefit
Simple	Single resource / basic DNS	No	Simplicity
Weighted	Load balancing / Canary testing	Yes	Granular traffic control
Latency	Global performance optimization	Yes	Best User Experience
Failover	Disaster Recovery (Active-Passive)	Yes	High Availability
Geolocation	Compliance / Localization	Yes	Legal/Cultural relevance

Decision Matrix / If–Then Guide

• If you need to test a new software version with 5% of users → Weighted.
• If you need to comply with data sovereignty laws → Geolocation.
• If you want to minimize “lag” for gamers in different countries → Latency.
• If you need an automated DR switch → Failover.
• If you want to return multiple healthy IPs for client-side load balancing → Multi-value.

Topics covered:

Summary of key subtopics covered in this guide:

• Simple vs. Complex Routing Logic
• Disaster Recovery Patterns (Active-Passive)
• Performance-based Routing (Latency)
• Location-based Routing (Geolocation/Geoproximity)
• Health Check Integration
• Alias Records and Zone Apex constraints